Re: [PATCH] xen/arm64: sysreg.h: Fix MISRA C 2012 Rule 20.7 violation

[Xenia Ragiadakou <burzalodowa@xxxxxxxxx>]

Hi Julien,

On 7/28/22 16:56, Julien Grall wrote:
> Hi,
>
> On 28/07/2022 14:49, Xenia Ragiadakou wrote:
> > The macro parameter 'v' is used as an expression and needs to be 
> > enclosed in
> > parentheses.
> >
> > Signed-off-by: Xenia Ragiadakou <burzalodowa@xxxxxxxxx>
> > ---
> >   xen/arch/arm/include/asm/arm64/sysregs.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/xen/arch/arm/include/asm/arm64/sysregs.h 
> > b/xen/arch/arm/include/asm/arm64/sysregs.h
> > index 54670084c3..f5a7269a27 100644
> > --- a/xen/arch/arm/include/asm/arm64/sysregs.h
> > +++ b/xen/arch/arm/include/asm/arm64/sysregs.h
> > @@ -461,7 +461,7 @@
> >   /* Access to system registers */
> >   #define WRITE_SYSREG64(v, name) do {                    \
> > -    uint64_t _r = v;                                    \
> > +    uint64_t _r = (v);                                              \
> I am failing to see why the parentheses are necessary here. Could you 
> give an example where the lack of them would end up to different code?
Here v is supposed to be used as an expression. So maybe the rule wants 
to enforce that in the macro we will pass an expression and not multiple 
statements (?) ... not sure.
> >       asm volatile("msr "__stringify(name)", %0" : : "r" (_r));       \
> >   } while (0)
> >   #define READ_SYSREG64(name) ({                          \
> Cheers,
--
Xenia